In a principal aspect the present invention relates to a tool and an associated kit of tools for removal of a broken spark plug from a cylinder head.
Motor vehicle internal combustion engines typically include spark plugs threaded into the engine cylinder head to provide an electric ignition spark for igniting combustible gasses within each cylinder. Each spark plug includes a distributor wire contact for attachment of a spark plug wire to a current source. The contact comprises the exposed end of a wire conductor axially extending through the plug leading to a spark gap at the tip of the plug inside the cylinder. Ignition of a fuel/air mixture in the cylinder is effected by a spark in the gap at the tip of the plug which projects through the cylinder head into the cylinder.
Spark plugs utilized for such an ignition system have a variety of constructions. Typically, a spark plug will include an axial conductor encased in a porcelain insulator. The conductor connects the outer end contact terminal of the plug to the spark gap tip. A threaded cylindrical body surrounds the insulator and supports and encases the component parts of the spark plug thereby enabling threaded insertion or removal of the plug from a threaded bore in the cylinder head of an internal combustion engine.
Spark plugs are typically periodically removed from the cylinder head to permit replacement. On occasion a plug will break during removal. Thus, the problem of removal from and replacement of spark plugs in a cylinder head is exacerbated by factors such as the design of the plug and the manner in which the plug is inserted into the cylinder head. This topic is described in Technical Service Bulletin #TSB 06-15-2 of the Ford Motor Company incorporated herewith by reference. The Service Bulletin discusses the problem associated with spark plug replacement and also suggests a solution to effect removal of a broken spark or damaged plug from the cylinder head of a motor vehicle engine.
An example of a tool used for removal of a broken spark plug from a cylinder head is described in an instruction memorandum for an OTC Product No. 6918 entitled “Ford Spark Plug Removal Tool” issued Oct. 17, 2012. The described spark plug removal tool employs the use of a collet for gripping the wire connector and porcelain body of a spark plug to effect removal from a cylinder head. The operating instructions and circular are incorporated herewith by reference.
Nonetheless, during attempted removal of a plug, the cylindrical spark plug tip may break and separate from the body of the threaded plug. As such, the tip remains positioned within the cylinder head and must be removed before a new plug can be threaded into the cylinder head.
Applicant's assignee developed tools to address various issues associated with the removal of a broken spark plug from the cylinder head of a motor vehicle, and, in particular, from the cylinder head of a vehicle of the type described in the Technical Service Bulletin referenced above, among others. Specifically, U.S. Pat. No. 7,814,814 entitled “Tool Kit for Removal of Broken Spark Plugs”, incorporated herein by reference, discloses a tool for removal of a broken spark plug from a cylinder head wherein the spark plug tip is separated from the remainder of the plug.
The subject matter of U.S. Pat. No. 7,814,814 is marketed by applicant's assignee, Lisle Corporation, as Spark Plug Removal Kit Number 65600. The kit was developed to facilitate the removal of certain spark plug components of a broken plug from the cylinder head of an engine. That is, during a plug removal procedure, the spark plug may occasionally break leaving the firing tip element in the head whereas the remainder of the spark plug may be successfully removed from the cylinder head. In this circumstance the insulator tip of the spark plug, which is typically a porcelain material, is pushed into the firing tip element to allow a firing tip removal tool to engage the firing tip and effect removal.
However, in certain instances removal of the spark plug may result in breakage of plug parts of the plug other than the tip causing such parts to remain within the cylinder head. For example, the porcelain insulator at the upper end of the plug may remain intact or partially intact within the cylinder head. When this occurs, the outer annular body of the plug may remain within the cylinder head along with various other components associated with the spark plug. The annular body may be removed by unthreading it from the head. However, the porcelain insulator may remain within the cylinder head along with other parts of the spark plug. Thus, the porcelain insulator must be removed from the cylinder head before a firing tip 38 can be removed using the tool such as described in U.S. Pat. No. 7,814,814. However, gripping the wire contact or wire connector which may remain lodged in the cylinder head is difficult and is compounded by the problem of removing the porcelain insulator. Needle nose pliers is often used by a mechanic to attempt to effect removal of the porcelain insulator. Again, this is a difficult operation to perform and may result in breakage of the component parts thus rendering the situation much more complex.